An object of the present invention is a system for the transfer of digitized images on sensitive support material or vice-versa. A further object of the present invention is a machine for obtaining the system. The innovation finds particular, if not exclusive application, in the field of high resolution images as, for example, in the making of films.
In this high resolution field, the resolution is meant to be considerable and of the professional type, and may be rightly considered, even if not in a limitative way, as being comprised within a value of 10 pixel pitch microns as the distance between two pixels. This value is also commonly defined as a raster of less than or equal to 10. Obviously, pixels, in computer language, are defined as known points which, together, compose an image.
The process itself of transferring the digitized image as pixels from a computer to a machine that carries out reproduction is here defined as the process of rasterization. One of the main, if not exclusive, purposes of this process is that of production of printed circuits.
However, nothing prevents the system and the machine from being used in any other field in which photographic film is required, as for example the typographical field, etc.
In the prior art, machines for sensitizing camera films with different photosensitive materials for a variety of purposes are known. The high resolution machines are based substantially on the use of a luminous head, or in the technically more advanced solution of a laser head, which sensitizes the photosensitive material. The machines include a cylindrical or flat support for the photosensitive material.
When a cylindrical support is used, there are two solutions. Either a drum is rotating and the head moves transversely in a back and forth movement, or the cylinder is fixed and is hollow, the photosensitive sheet is inserted inside the cylinder, and the head is axially placed in the cylinder and the head not only moves alternatively in a back and forth movement, but also rotates. In this way, with the respective movements suitably coordinated, the digitized image is reconstructed by carrying respective points, one behind the other, on the basis of respective coordinates, up to the complete reconstruction of the image.
The solution on the flat support is less used because it is considered to be complex and expensive, as compared to the solutions using the cylindrical support and utilizes substantially the same principle. A difference is that the solution relying on the flat support works as a plotter in which a plotting head moves on a surface of the flat support along the respective coordinates, just like a drawing plotter in a computer.
All of the above-mentioned solutions are expensive and difficult to implement, and in any case, require lengthy reproduction times. Further, although to resolution is obviously higher in the laser versions, the time and costs for the purchase and maintenance of these machines remains very high, due to the presence of a substantial number mechanical parts in motion.
In analyzing all of these types of machines, the presence of only one operating head can be noticed. The one operating head can send one or more points at a time, in logical succession, up to completion of the entire image on the surface chosen for the (exposure, starting, for example, from an upper angle until reaching a lower diametrically opposite angle. The logical succession of these steps makes practically impossible to increment considerably the operative speeds of these machines.
GB-2187855 discloses a photoplotter using light valve device using a single light source, a support for a sheet of photosensitive material for exposure and a light valve device interposed between the light source and the sheet to divide the sheet image in a plurality of spaced subareas or pixels, the light transmissivity of which are individually controlled through an associated computer to cause the exposure to be that of a desired graphic or artwork. The light valve device may be moved relative to the sheet to expose areas corresponding to those originally associated with the space between the pixels. This solution is very interesting but has the drawback of not being able to control the entire figure because of the shadow of the light valve device.
WO 9324396 A discloses a method and device for retaining a thin medium between two bodies. In particular, with an emphasis on faster and better exposure of the medium, electronic chips have been developed by means of which a plurality of selectively modulable light channels can be romed. These chips may be used for building a rod transversely to the medium for exposure, so that the medium is illuminated in a coherent line in its entire width (U.S. Pat. Nos. 4,899,222, 5,030,970, GB 187855).
U.S. Pat. No. 4,176,947 discloses a step and repeat mechanism. In particular, it concerns an apparatus for moving sheet material, primarily microfiche, into a plurality of X and Y axis position by means of a gas cushion formed on a plate in which the sheet material is shifted by means of ducted gas jets or sweeps.
The aim of this invention is to avoid the above-mentioned drawbacks, and in particular to make an inexpensive, reliable, and fast machine that requires minimum maintenance, is easy to use, and in which the resolution level can be the highest without endangering in any way a necessary suitable resolution level, as mentioned above.
These and other aims are reached as claimed by a system for the transfer of digitized images from a computer to photosensitive image support material or vice-versa. The system comprises an active flat plate means for the exposure or detection of an image, on which can be placed a sheet which must be exposed or subjected to detection which involves a plurality (n) of illuminable sources of punctiform exposure or detectors, arranged in a fixed way in a raster of (n) squares. The plurality (n) of illuminable sources of punctiform exposure or detectors are connected/connectable to a digital system of the computer image, and able, by means of suitable software to be activated. Each of the plurality of sources or detectors only operates on one point, corresponding to only one pixel of a square at a time. Each square (n) of the raster being able to include a plurality of pixels or points of the image equal to (x), and in such a way that the total number of pixels or points of the entire image is equal to (nx).
The system also comprises support means for the sheet on the active plate means, and means for moving the active plate and/or the image sheet. The means for moving being able to move at least one of the active plate means and the sheet with respect to each other according to digitized coordinates corresponding to at least the portion (n) of the entire image to be digitized, and to activate for successive points, one adjacent to other illuminable sources of punctiform exposure or detector, each time and step by step for exposure on the photosensitive material, so that illuminable sources of punctiform exposure or detectors, sensitize/detect the entire surface corresponding to its own square (n) of the sheet to be treated. This results in the entire image being sensitized in an exact reproduction of the original with the aid of the (n) luminous sources/detectors, each one displaced in connection with each square of the raster.
In this way, there is an immediate advantage of increasing the transfer and sensitizing speed by many times, corresponding to the number of sections (n) of the raster. This increase in speed obviously considers the theoretical side and the fact that the electronic transfer operation moves at the speed of light. Considering further, that there is more complex processing and calculation associated with this system, the operative times are reduced by more than 70%, with the further advantage of an important simplification of the system, lower manufacturing costs (for the active plate and the use of common xe2x80x9cLEDsxe2x80x9d), etc.
Advantageously, the movement is communicated to the photosensitive sheet which is kept suspended among the active plate and the counter-plate in a cushion of air. In this way, the movement is very slight, fast and quick and does not involve moving considerable masses. Furthermore, the photosensitive material does not touch the surface of the active plate and is not damaged.
Advantageously, the air bearing is made by means of a plurality of punctiform air-jets made in the opposite plates so that the sheet is kept suspended between the two surfaces, while the movement mechanism will clamp the sheet only on one side for its simple and limited movement.
These and other advantages will appear from the following embodiments described with the aid of the included drawings whose details are not to be considered limitative, but only supplied as an example.